Method and apparatus for transcoding between different speech encoding/decoding systems using gain calculations
First Claim
1. A code converting method for converting a first code sequence conforming to a first system to a second code sequence conforming to a second system, the method comprising:
- receiving first gain information from the first code sequence;
decoding the first gain information from said first code sequence to generate decoded gain;
correcting the decoded gain to generate corrected decoded gain;
generating second gain information in said second code sequence based on the corrected decoded gain, said decoded gain and a gain read out from a gain codebook in said second system; and
outputting the second gain information.
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Abstract
A code converting apparatus for converting a first code sequence conforming to a first system to a second code sequence conforming to a second system, in which a speech decoding circuit acquires a first linear prediction coefficient and the information on an excitation signal from the first code sequence, and actuates a filter having the aforementioned first linear prediction coefficient with the excitation signal obtained from the information on the excitation signal, to generate a first speech signal. A gain code generating circuit calculates a gain minimizing the distance between a second speech signal, obtained from the second code sequence, and the first speech signal (optimum gain), and corrects the optimum gain. The gain code generating circuit then finds the gain information in the second code sequence, using an evaluation function which will reduce time variations of the gain of the second system.
4 Citations
19 Claims
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1. A code converting method for converting a first code sequence conforming to a first system to a second code sequence conforming to a second system, the method comprising:
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receiving first gain information from the first code sequence; decoding the first gain information from said first code sequence to generate decoded gain; correcting the decoded gain to generate corrected decoded gain; generating second gain information in said second code sequence based on the corrected decoded gain, said decoded gain and a gain read out from a gain codebook in said second system; and outputting the second gain information. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A code converting apparatus for converting a first code sequence conforming to a first system to a second code sequence conforming to a second system, said apparatus comprising:
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a gain code demultiplexing circuit receiving first gain information from the first code sequence; a gain decoding circuit decoding the first gain information from said first code sequence to generate decoded gain; a decoded gain correcting circuit correcting the decoded gain to generate corrected decoded gain; a gain encoding circuit generating second gain information in said second code sequence based on the corrected decoded gain, said decoded gain and a gain read out from a gain codebook in said second system; and a gain code multiplexing circuit outputting the second gain information. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A computer program product stored in a medium used by a computer, that comprises a code converting apparatus for converting a first code sequence, into a second code sequence conforming to a second system, comprising a program to cause said computer to execute:
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(a) a process of receiving first gain information from the first code sequence; (b) a process of decoding the first gain information from said first code sequence to generate decoded gain; (c) a process of correcting the decoded gain to generate corrected decoded gain; (d) a process of generating second gain information in said second code sequence based on the corrected decoded gain, said decoded gain and a gain read out from a gain codebook in said second system; and (e) a process of outputting the second gain information. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification